Snapped head stud

Discussion in 'Technical Q&A' started by timthetooth, May 22, 2004.

  1. timthetooth

    timthetooth Rookie

    Dec 18, 2003
    I have a problem with my 400i engine. One of the head studs has broken off just below the level of the block. The engine is in the car still. I am considering the following ways of sorting this out and would be grateful for any advice and comments you may have.

    1. Drill out the remaining part of the stud, try and remove the final threaded part with a stud extractor. If that fails, drill out the whole stud, bore the stud hole oversize, retap the block and use a helicoil to secure new stud. The depth of the stud makes this difficult to do precisely, even with the drill secured to the block.

    2. Drill out broken stud to 4cm, retap block at this level and have a new stud specially made to fit.

    3. Cut my wrists now to avoid further disappointments!

    I am a bit worried that following course 2 may cause problems with the block fracturing, in which case course 3 will be the only way out.

    Please help me!!!!!!

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  3. henryk

    henryk Formula Junior

    Dec 9, 2003
    Door County, WI
    If the stud is in SO tight, that it broke, I doubt that the extractor idea will work.

    Use a small die grinder, and put a dimple in the MUST be in the center of it. This will guide any drill bit down the center. You must make sure the drill bit is perpendicular to the stud lenght. Use a small drill bit and drill down the center of the stud, all the way through Then, use a bigger bit, and go through the stud. Continue using larger size bits, till you get to one that is slightly smaller than the stud hole. Often the remains will now come out.

    If the thread, in the block is damaged, then you will have to HeliCoil it. You will have to use the drill bit that they recommend, that will coincide with the original stud thickness, and thread, when finished. I have done this, and the hole drilled, for the HeliCoil, is only minimally larger than the original hole. Of course, the stud will still have to come out before drilling for the HeliCoil.
  4. Newman

    Newman F1 World Champ
    Professional Ferrari Technician Consultant Owner

    Dec 26, 2001
    Full Name:
    You may very well have to yank the engine and have a machine shop extract it for you. Consider that route before you butcher the block. Sometimes its just better to bite the bullet and have someone with access to the right equipment do the job. I cant think of a worse situation and Im dealing with engines daily. Sometimes welding something like a dowl onto the end of the stud gives you something to grab as well as applying heat to the block near the threaded portion of the stud, not to mention praying alot.
  5. ferrarifixer

    ferrarifixer F1 Veteran

    Jul 22, 2003
    Full Name:
    Phil Hughes
    I agree with Newman. Try welding a large nut onto the top of the stud. You should be able to use a large enough nut to weld from inside and bridge the gap to reach the top of the stud.

    This will give you a hexagon to turn the stud and hopefully enough heat around the problem to shift it.

    It will be a bastard though.......
  6. timthetooth

    timthetooth Rookie

    Dec 18, 2003
    Thanks for the advice chaps.
    The nut welded to the stud idea I have already tried. Unfortunately the stud broke again and is now below the surface of the block. I am going to contact an engineer I know and see if there is a possibilty of mounting a drill on the block.
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  8. thecarreaper

    thecarreaper F1 World Champ
    Silver Subscribed

    Sep 30, 2003
    if it were me: !) warm the block 2) soak the area in marvel mystery oil or similar 3) come back in a day, warm the block some more 4) drill it #40 as deep as possible MUST BE STRAIGHT 5) use a #2 easy out . one time i drilled out one side of an Allen key and installed a easy out ( backwards) i put a box end ratchet wrench on the allen key and removed the stud ( aluminum chevy block.) never fun, good luck to ya!
  9. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    B.C., Canada
    Sitting here thinking about this, with all of this talk of drilling, I can only suggest that the engine be removed and stripped down, because it would be impossible to catch all drill shavings while in place. Then you'd have the problem of little shards of metal that could float around and scratch a cylinder bore, or a bearing... Bigger problems.

    With the engine out and stripped down, use an "easy-out" (bolt extractor) in the old stud and a localised application of heat to the block in the area of the stud from an oxy-acetylene torch, spray with a penetrating oil and remove. It will come out then. Warpage from the heat should be minimal and could be cleaned up on a mill. I do this all of the time at work (on less critical pieces than an engine block, but this process takes minutes regardless).
  10. sjtom

    sjtom Karting

    Jan 5, 2004
    San Jose, California
    Full Name:
    When all else fails..... I had the same problem, didn't want to risk damaging the block with excess heat or rethreading, used an EDM shop to take out center of bolt, then extract remainder. Suggested by a F racing shop, worked fine but expensive.
  11. lbanez

    lbanez Rookie

    May 11, 2004
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